The tingling sensation and movement of the jaw upon reacting to extasy. Also refered to as 'Gurning'. It is the chewing of the lips and random motion of the mouth.
Brad: Yo Harry, you got any diddlies?
Harry: Yea man, Try one of these new bad boys.
*Half an Hour Later*
Brad: Harry they are the Shiznik.
Harry: Safe but stop with the 'Jawgasm', you guna get clocked.
It is said of the situation where a person has the bad luck to make contact with his testicles against an undefined surface or object, intentioned or not.
Given the nature of the word, it is more appropriate to design cases where the interaction is made with a moving object, for example, a ball.
Although it is extremely painful for the victim, it tends to be considerably funny to people who witness it.
Today in the baseball game the pitcher took a nutshot; the baseball hit him in the nuts.
Man, I just watched the funniest nutshot video ever.